The Adolescent Brain Cognitive Development (ABCD) study is the largest long-term study of child health and brain development in the US, consisting of a Coordinating Center, a Data Analysis and Informatics Resource Center, and 21 research sites. The ABCD Study has enrolled a diverse cohort of 11,878 9-10-year-olds and will continue to track their biological and behavioral development through adolescence into young adulthood. All participants receive neuroimaging, neuropsychological testing, bioassays, and detailed youth and parent assessments of substance use, mental health, physical health, and culture and environment. In March 2020, when our participants were ages 11-13, the world became substantially affected by the COVID-19 pandemic, leading to an upheaval in the economy and the lives of almost every family. Most U.S. schools closed to reduce viral spread. Many parents incurred changes in work (e.g., working-from-home, longer shifts, reduced wages, job loss). Some services and support systems became disrupted. And, the number of confirmed cases and deaths have continued to surge. The massive multifaceted impact of this unprecedented event has the potential to affect today?s children for decades to come. Here, we propose to leverage ABCD?s infrastructure, cohort, and existing protocol to rapidly characterize the impacts of the COVID-19 pandemic on each child in the study. In this proposal, we will capitalize on funded (NSF; PI Tapert) and pending supplements to administer queries to all ABCD participants and their parents about the impact of the pandemic on their lives (family level impact) by also incorporating publicly and privately available measures of community-level COVID-19 impacts. For participants? neighborhoods (e.g., census tract, county, state), we will geocode measures of incidence, spatial distancing, changes in (un)employment, and timing of implementation of state and/or local policies on mitigation practices. By collecting this situational information at the family and community levels as soon as possible, we can use existing ABCD data to examine perturbations in developmental trajectories of brain functioning, cognition, substance use, academic achievement, social functioning, and physical and mental health. Specifically, we will (1) focus on characterizing the nature and variability of the community and regional impact of COVID-19, based on geocoding of ABCD participants? neighborhoods (i.e., current home address) and (2) determine how community-level and family-level impacts of COVID-19 differentially influence stress, cognition, and mental health during and after the pandemic. We will analyze (1) the interactions between family- and community-specific impacts on ABCD participants? immediate stress and mental health during the pandemic, (2) the extent to which such potential impacts are associated with each other, and (3) how both community and family factors (e.g., SES, neighborhood characteristics) may serve as protective factors. This unprecedented crisis provides an opportunity to exploit ABCD?s infrastructure and scientific rigor to discern critical dimensions of development not previously envisioned.